The invention relates to an adjusting device of a disk brake, and to a disk brake equipped with such a device.
Adjusting devices on disk brakes are used to compensate for the brake linings which become thinner owing to wear and which become displaced in the direction of the disk brake in order to set a desired venting play so that the working stroke necessary for braking remains constant.
Adjusting devices of the generic type are known from the European patent EP 0 531 321 B1. For the individual details of the functioning of the adjusting device of the generic type and an example of a disk brake which can be activated by a rotary lever and for which the adjuster of the generic type, but also the adjuster according to the invention, is suitable, reference is made to the entire contents of this document. An adjuster of this generic type is shown in FIG. 6.
The adjusting devices illustrated in EP 0 531 321 B1 have proven satisfactory. They are arranged in the interior of rotatable spindles which are fitted with pressure elements which act on one of the brake linings. They are suitable for disk brakes of various types having one or more rotatable spindles have.
During an adjusting movement when braking, the adjusting devices of the generic type transmit, by means of an output bushing, a torque to the rotatable spindle which is fitted with the pressure element at its end facing the brake disk, said pressure element acting on the lining carrier plate of a brake lining. The rotational movement of the rotatable spindle causes the pressure element to be displaced axially in the direction of the disk brake in order to compensate for a reduction in the thickness of the brake lining material which is caused by wear. In order to ensure the adjusting function, the adjusting devices generally have a freewheel so that the adjuster does not rotate backwards when the brake is released, and an overload coupling which responds when the pressure elements are applied to the brake lining.
The output bushing of the prior art is provided on its outer circumference with at least one radially projecting tooth-like tooth for engaging in at least one corresponding tooth-like groove on the inner circumference of the rotatable spindle. This arrangement has proven effective.
The prior art also includes German patent DE 1600182 B2, an example of the prior art in adjusting devices. This document presents an elastic support of lugs by means of springs. When the tension of the application device is released, the springs press the lugs one against the other. However, the rotatable spindle does not act on a brake lining by means of a pressure element.
Against this background, the object of the invention is to further develop the adjusting device of the generic type in such a way that its function is optimized still further.
This object is achieved by the invention as follows.
In one output tooth arrangement, the at least one tooth and/or the at least one groove is/are embodied so as to be elastically compressible, and/or the at least one tooth and/or the at least one groove is/are supported elastically one against the other, and/or a plurality of the teeth and/or a plurality of groove sections (9, 9′) are supported elastically (in particular in a sprung fashion) one against the other.
According to this, the output tooth arrangement, in particular at least one tooth and/or the at least one groove, are embodied so as to be elastically compressible and/or supported elastically one against the other.
According to the invention, an adjusting device is implemented which compensates without play for all fabrication tolerances at the interface between the output sleeve of the adjusting device and the adjusting rotatable spindle (typically a threaded tube) without jamming occurring when the adjuster shaft is rotated and slid.
In contrast to this, even the adjusting properties in the case of shaking stresses, rotation and sliding of the adjuster shaft with respect to the threaded tube or rotatable spindle shaft, repeat attempts as a result of static application and their combination are positively influenced.
The invention is particularly advantageously suitable for an adjusting device with an output bushing which engages in an axial opening in the rotatable spindle and which on its outer circumference has at least one tooth which engages in a groove on the inner circumference of the rotatable spindle. However, it can also theoretically be used in other arrangements if, for example, the rotatable spindle has in certain sections an outer toothing which intermeshes with an output wheel of the adjusting device (which can also have an electric drive).
Play-free shaft-hub connections are known per se. Their use in adjusting devices for brakes has previously not been considered. In this respect, the following are specified DE 1921099 A, JP 4254045 AA, DE 1205345 B and DE 19855538 A1.
In particular, the effect of the invention can be implemented by means of a spring which prestresses in a sprung fashion two or more teeth, which can move relative to one another, of the output tooth arrangement and/or two outer edge sections, which can move relative to one another, of a single tooth or of a plurality of teeth.
According to a particularly functionally reliable alternative, the at least one single-part or multi-part tooth preferably has the two outer edge parts which can move relative to one another and between which at least one or more compression spring(s) is/are arranged, which compression springs press the two outer edge parts apart from one another in such a way that the two outer edges bear without play against the inner edges of the groove.
In this context, the one outer edge part is preferably formed in one piece with the output bushing, and the other outer edge part is guided in a moveable, in particular slideable, fashion on the outer circumference of the output bushing.
According to an alternative variant, which is easy to implement and nevertheless functionally reliable and also of course inventive, the output bushing is adjoined axially by a toothed disk whose diameter corresponds to the diameter of the output bushing and which has at least one tooth which corresponds to the tooth of the output bushing, and the groove of the rotatable spindle extending axially into the region of the tooth of the toothed disk. Here, the toothed disk is designed so as to be rotatable relative to the output bushing and the toothed disk and the output bushing are prestressed relative to one another by means of a spring, in particular a torsion spring, so that the tooth arrangement easily has at least two teeth which are spring prestressed relative to one another and thus elastically compressible relative to one another. Possible springs are, for example, disk springs or helical springs.
The rotation position between the toothed disk and the output bushing can expediently be secured by means of a toothed coupling in order to fix a desired degree of prestress.
In a further embodiment it is also possible to provide for the output part of the adjuster to be embodied as a sleeve with an inner profile, and for the rotatable spindle to have an outer profile, the output part of the adjuster then engaging around the rotatable spindle and the outer teeth the rotatable spindle engaging in grooves of the output part of the adjuster. In this arrangement, the invention can also be used in a quasi inverted manner.
According to a further preferred variant, an annular disk is fitted onto, or arranged on, an axial end of the rotatable spindle with one or more of the grooves, the inner circumferential profile of said annular disk corresponding to the inner circumferential profile of the rest of the spindle, that is to say also having the groove, the annular disk and the spindle being prestressed relative to one another by means of a sprung element. The groove is thus also capable of being compressed in itself, as it were in the manner of multiple parts (one part in the annular disk and one in the rotatable spindle). This embodiment variant also implements the advantages of the invention.
It is finally also conceivable for a spring which elastically prestresses the tooth and the groove one against the other to be arranged directly between one of the outer edges of a tooth of the output part and the inner edge of the groove.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.